# HG changeset patch
# User Augie Fackler <augie@google.com>
# Date 2017-03-08 23:31:33
# Node ID 79715ba22f9c873d0425894091c318ca958da8e5
# Parent  063d7957fa1299b6ee51384c9188acc66aea9d6a

help: avoid mutating passed-in `keep` list in `formattedhelp`

diff --git a/mercurial/help.py b/mercurial/help.py
--- a/mercurial/help.py
+++ b/mercurial/help.py
@@ -618,6 +618,8 @@ def formattedhelp(ui, name, keep=None, u
     """
     if keep is None:
         keep = []
+    else:
+        keep = list(keep) # make a copy so we can mutate this later
     fullname = name
     section = None
     subtopic = None